The initial objective of the study is to carry out laboratory investigations using in vitro caries models to demonstrate whether salivary pellicle is a major inhibitor of caries. We will attempt to relate this inhibition to the presence of specific proteins and/or lipids in pellicle or saliva. The secondary objective is to examine saliva from caries-prone, caries-resistant, and geriatric subjects for the presence of components identified in the in vitro studies and to investigate these parameters as possible caries predictors. Such information may lead to improved caries-preventive measures or to enhanced prognostic procedures for patients with salivary gland malfunction. In order to achieve these objectives the specific aims are: (1) To use an in vitro caries model, and (2) an apatite dissolution model, to study the caries inhibitory effect of (a) whole saliva, (b) specific fractions and components separated by biochemical means from whole saliva or glandular saliva. (3) When 1 and 2 have been established, to investigate whether saliva from a range of subjects contains the specific components identified as caries inhibitors. These components or combinations of components (proteins/lipids) will then be examined from these subjects in the caries in vitro model and the apatite dissolution model. (4) To collect saliva from subjects in the categories of caries-prone, caries-resistant, and a geriatric population with reduced salivary function, and to examine their saliva by biochemical assays for the active components. The subjects will be drawn from other proposals (Dr. D. Leverett, P.I., Dr. S. Handelman, P.I., and Dr. C. Meyerowitz, P.I.). Specific inhibitory component presence (1 and 2 above) will be examined in relation to age and caries status. (5) To use the animal model (Dr. W.H. Bowen, P.I.) to study these specific inhibitory components in relationship to induced hyposalivation. (6) If a relationship is found between specific components of saliva and age of caries status, this concept will be developed as a caries diagnostic tool for caries-susceptible people. This study, together with other studies in the Rochester Cariology Center, will provide chemical and microbiological parameters for the improved diagnosis and treatment of caries-susceptible subjects.